1. Field of Invention:
This invention relates generally to computer terminals provided with a keyboard and an electronic display, and more particularly to a desktop terminal having an electronic display module whose angular position is adjustable so as to orient the display relative to the operator of the terminal to render the display fully visible under prevailing ambient light conditions.
2. Status of Prior Art:
A computer terminal is a device that allows a user of a data processing system to gain access to the system at a remote location. Remote terminal data processing systems, often referred to as teleprocessing systems, represent a form of information processing in which a multiplicity of remote terminals access a computer by way of communication lines. Such teleprocessing systems which are now widely used can provide various data processing services to many locations without the need for a computer at each location.
In a teleprocessing system of the inquiry and response type, the computer functions as a mass storage facility which can be accessed via a communication network, the files of the computer being updated automatically. Examples of systems of the inquiry and response type are the various airline and hotel reservation systems in which the user enters a query at a terminal, thereby causing the computer to search its files and to send back the requested information to the remote terminal.
In the well known SABRE II reservation system for American Airlines, nearly 2000 terminals at various locations throughout the country are supported by two IBM computers, one of which is a backup. Approximately a million inquiry messages are handled daily.
The concern of the present invention is with a desktop computer terminal provided with a keyboard by which an operator is able to enter data, and an electronic display to present to the operator data entered into and received by the computer terminal. Among the commercially available types of electronic displays for desktop computer terminals are the light-emitting-diode (LED) display and the liquid-crystal-display (LCD). Such displays lend themselves to compact and portable design configurations, unlike video displays which require a cathode ray tube.
Human factors or human engineering deals with the human-machine interface. The question that arises in a user-display interface is whether the display can be read easily, accurately and without operator fatigue. Even assuming that in a computer desktop terminal the electronic display is such that the letters, numbers, characters and other elements of the display in regard to size and font are highly visible and free of flicker, the display may nevertheless not be clearly visible to the operator, and indeed may be very difficult to read. (See: Electronic Displays by E. G. Bylander - Texas Instruments Electronic Series, McGraw Hill Book Co. 1979 - Chapter 3 - Display Human Factors.)
An operator sitting before an electronic display covered by a window in which numerals, letters and characters are exhibited in black against a grayish background, as in a typical LCD display, will find that the readability of the display depends in large measure on the angle assumed by the display window relative to incident ambient light.
To give a simple analogy: With a digital watch having an LCD time display, it is a common experience for the user to find that at most angles at which the dial of the watch is viewed, light rays reflected from the watch crystal interfere with the visibility of the display. The dial can best be read at that angle at which rays reflected from the watch crystal are directed away from the eyes of the viewer.
The same problem arises in a conventional electronic display incorporated in a desktop computer terminal. Because the electronic display occupies a fixed position determined by the placement of the computer terminal on the desk, an operator may find the display difficult if not impossible to read under prevailing ambient light conditions.
It is for this reason that an operator may try to prop up the desktop terminal to find an angle at which the visibility of the display is improved. But an angle suitable for one operator may not be acceptable to another who is shorter or taller. Moreover, the terminal keyboard is best operated when the terminal lies flush on the desktop and is not angled with respect thereto.
Another common approach to this problem is to provide an electronic display unit that is separate from the keyboard section of the desktop computer terminal The advantage of a separate electronic display unit is that the display may be pivotally supported on a stand so that it can be oriented relative to the operator. But where the desideratum is a highly compact, self-sufficient, desktop computer terminal, this solution is not acceptable.
Another drawback of a separate electronic display unit is that it requires a plug-in cable connection between the unit and the terminal, and this may result under certain circumstances in a poor or defective connection therebetween.